The primary objective of the proposed research is to develop a valid animal model for investigating the etiology and treatment of alcoholism in humans. This will be accomplished by investigating the effects of a chronic and socially complex form of stress, induced by crowding, on the voluntary consumption of ethanol by rats. The hypothesis, based on preliminary work by the principal investigator, is that crowding-induced stress will lead to greater consumption of ethanol than has been obtained under voluntary conditions in previous experiments. The second objective is to investigate the tension reduction hypothesis of alcoholism more systematically than in previous experiments. This will be accomplished by measuring the effects of increasing levels of crowding-induced stress on behavioral arousal (measured by time-sampling observations ad physiological arousal (measured by urine 17-hydroxycorticosteroid levels) throughout the experiment, to determine if these measures are correlated with ethanol consumption. The third objective is to analyze individual differences in ethanol consumption to determine if some rats, under the same environmental conditions, are more susceptible to excessive consumption than others. Large individual differences would suggest that animal models for studying alcoholism will have to be designed and interpreted with this possibility in mind.